Coordinate measurement machine with vibration detection

ABSTRACT

An articulated arm system can include an articulated measuring arm with a plurality of interconnected support arm segments. The arm segments can be moveable about a plurality of axes. A plurality of rotational angle sensors can mount on the arm and be configured to measure rotational position between the support arm segments. Additionally, a vibration detection device can attach to the arm near an end of the arm. The vibration detection device can be operatively connected to the sensors such that the sensors output a rotational position upon detection of a new vibration exceeding a threshold amplitude.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority benefit under 35 U.S.C. §119(e) toU.S. Provisional Patent Application Ser. No. 61/221,973 (filed Jun. 30,2009), the entirety of which is hereby expressly incorporated byreference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present application relates to measuring devices, more specificallyto coordinate measurement machines.

2. Description of the Related Art

Portable coordinate measurement machines (PCMMs) such as articulated armPCMMs can be used to perform a variety of measurement and coordinateacquisition tasks. In one common commercially-available PCMM, anarticulated arm having three transfer members connected by articulatingjoints allows easy movement of a probe head or tip about seven axes totake various measurements. In operation, when the probe head or tipcontacts an object the PCMM outputs to a processing unit data regardingthe orientation of the transfer members and articulating joints on thearticulated arm. This data would then be translated into a measurementof a position at the probe head or tip.

Typical uses for such devices generally relate to manufacturinginspection and quality control. In these applications, measurements aretypically taken only when a measuring point on the arm is in contactwith an article to be measured. Contact can be indicated bystrain-gauges, static charge, or user-input. Such devices have beencommercially successful. Still there is a general need to continue toincrease the accuracy of such instruments.

SUMMARY OF THE INVENTION

As described in further detail herein, systems and methods are disclosedovercoming the shortcomings of the prior art and having certainadvantages. Using strain-gauges to indicate contact can be problematicwhere the deflection of the gauge introduces additional error to ameasurement of the position. Static charge might not be available in allapplications. User-input may introduce error, as there may be additionaldelay between initial contact and user-input, and further in that theuser-input itself (e.g. actuating a button) may cause further movementof the PCMM. Further, devices that generate their own vibrations adderror to their measurements. In light of the prior methods discussedabove, there is a need for a superior system and method for detectingcontact.

In one embodiment an articulated arm system can include an articulatedmeasuring arm with a plurality of interconnected support arm segments.The arm segments can be moveable about a plurality of axes. A pluralityof rotational angle sensors can mount on the arm and be configured tomeasure rotational position between the support arm segments.Additionally, a vibration detection device can attach to the arm near anend of the arm. The vibration detection device can be operativelyconnected to the sensors such that the sensors output a rotationalposition upon detection of a new vibration exceeding a thresholdamplitude.

In another embodiment a method of operating an articulated arm system isprovided. An item to be measured can be contacted with an articulatedmeasuring arm. The arm can include a plurality of interconnected supportarm segments moveable about a plurality of axes. Upon contact with theitem, a new vibration can be sensed at an end of the measuring arm. Inresponse to the new vibration, a triggering signal can be generated. Inresponse to the triggering signal, a position of the end of themeasuring arm can be automatically measured. In some embodiments thestep of automatically measuring can include sensors outputting therotational position of the support arm segments. In other embodiments,the step can also include storing or processing the outputted rotationalpositions.

In a further embodiment, a probe is configured for use with a coordinatemeasurement machine. The probe can include a probe tip which includes anaccelerometer mounted within it. The probe tip can connect to a probebody via a probe neck. Further, a mounting portion can mount the probebody to a coordinate measuring machine. The mounting portion can includea connect device and a data port. The connect device can form aninterengaging structure with a coordinate measuring machine to form aphysical connection. The data port can provide data transfer between theprobe and the coordinate measuring machine.

For purposes of this summary, certain aspects, advantages, and novelfeatures of the invention are described herein. It is to be understoodthat not necessarily all such advantages may be achieved in accordancewith any particular embodiment of the invention. Thus, for example,those skilled in the art will recognize that the invention may beembodied or carried out in a manner that achieves one advantage or groupof advantages as taught herein without necessarily achieving otheradvantages as may be taught or suggested herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Further objects, features and advantages of the invention will becomeapparent from the following detailed description taken in conjunctionwith the accompanying figures showing illustrative embodiments of theinvention, in which:

FIG. 1 is a perspective view of an embodiment of a coordinate measuringmachine (CMM);

FIG. 2 is a perspective view of another embodiment of a CMM;

FIG. 3 is a schematic illustration of an embodiment of a probe for theCMM of FIG. 1 or 2;

FIG. 3A is a schematic illustration of an embodiment of a probe for theCMM of FIG. 1 or 2;

FIG. 4 is a schematic illustration of another embodiment of a probe forthe CMM of FIG. 1 or 2; and

FIG. 5 is a schematic illustration of another embodiment of a probe forthe CMM of FIG. 1 or 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following detailed description presents various descriptions ofcertain embodiments of the present teachings described herein. However,the inventive scope of the present teachings can be embodied in amultiplicity of different ways as defined and covered by the claims. Inthis description, reference is made to the drawings wherein like partsare designated with like numerals throughout.

FIG. 1 illustrates one embodiment portable coordinate measuring machine(PCMM) 10. While the illustrated embodiment is a portable coordinatemeasuring machine, it should be appreciated that certain embodiments canbe applied in the context of a non or semi portable CMM. In theillustrated embodiment, the PCMM 10 comprises a base 20, a plurality ofrigid transfer members 24, 26, 28, a coordinate acquisition member 30and a plurality of articulation members 40, 42, 44, 46, 48, 50connecting the rigid transfer members 24, 26, 28 to one another. Eacharticulation member is configured to impart one or more rotationaland/or angular degrees of freedom. Through the various articulationmembers 40, 42, 44, 46, 48, 50, the PCMM 10 can be aligned in variousspatial orientations thereby allowing fine positioning of the coordinateacquisition member 30 in three dimensional space.

The position of the rigid transfer members 24, 26, 28 and the coordinateacquisition member 30 may be adjusted using manual, robotic,semi-robotic and/or any other adjustment method. In one embodiment, thePCMM 10, through the various articulation members, is provided withseven rotary axes of movement. It will be appreciated, however, thatthere is no strict limitation to the number of axes of movement that maybe used, and fewer or additional axes of movement may be incorporatedinto the PCMM design.

In various embodiments, the coordinate acquisition member 30 comprises acontact sensitive member or contact probe 32 configured to engage thesurfaces of a selected object and generate coordinate data on the basisof probe contact. In some embodiments, the contact probe 32 can be ahard probe, which can be substantially rigid and solid. Devices ormodules for detecting and/or indicating contact can be disposed outsidethe hard probe, as discussed further below. As also discussed furtherbelow, the probe contact can be indicated by a detected vibration on,near, or within the probe. In further embodiments, the coordinateacquisition member 30 may additionally comprise other methods anddevices for detecting position such as a remote scanning and detectioncomponent that does not necessarily require direct contact with theselected object to acquire geometry data. In one embodiment, a lasercoordinate detection device (e.g., laser camera) may be used to obtaingeometry data without direct object contact. It will be appreciated thatvarious coordinate acquisition member methods and devices for detectingposition and/or contact including: a contact-sensitive probe, aremote-scanning probe, a laser-scanning probe, a probe that uses astrain gauge for contact detection, a probe that uses a pressure sensorfor contact detection, a probe that used an infrared beam forpositioning, and a probe configured to be electrostatically-responsivemay also be combined with a vibration detection probe (as describedbelow) for the purposes of coordinate acquisition.

In other embodiments, one or more of the rigid transfer members 24, 26,28 comprise a composite structure that includes an inner portion and anouter exoskeletal portion. In such an arrangement, the inner portion ofthe rigid transfer members 24, 26, 28 are interconnected to one anotherthrough articulation members that provide the ability to position thecoordinate acquisition member 30 in a variety of different orientationsin three dimensional space. The outer portions surrounding the variousinner portions of the rigid transfer members 24, 26, 28 form anenvironmental barrier that at least partially encloses segments of theinner portions. In one aspect, the inner portions are configured to“float” inside the corresponding outer portions.

As is known in the art, the position of the probe 32 in space at a giveninstant can be calculated by knowing the length of each member and thespecific position of each of the articulation members 40, 42, 44, 46,48, 50. Each of the articulation members 40, 42, 44, 46, 48, 50 can bebroken down into a singular rotational degree of motion, each of whichis measured using a dedicated rotational transducer. Each transduceroutputs a signal (e.g., an electrical signal), which varies according tothe movement of the 40, 42, 44, 46, 48, 50 in its degree of motion. Thesignal can be carried through wires or otherwise transmitted to the base20. From there, the signal can be processed and/or transferred to acomputer for determining and recording the position of the probe 32 inspace.

In one embodiment, the transducer can comprise an optical encoder. Ingeneral, each encoder measures the rotational position of its axle bycoupling is movement to a pair of internal wheels having successivetransparent and opaque bands. In such embodiments, light can be shinedthrough the wheels onto optical sensors which feed a pair of electricaloutputs. As the axle sweeps through an arc, the output of the analogencoder can be substantially two sinusoidal signals which are 90 degreesout of phase. Coarse positioning can occur through monitoring the changein polarity of the two signals. Fine positioning can be determined bymeasuring the actual value of the two signals at the instant inquestion. In certain embodiments, maximum accuracy can be obtained bymeasuring the output precisely before it is corrupted by electronicnoise. Additional details and embodiments of the illustrated embodimentof the CMM 10 can be found in U.S. Pat. No. 5,829,148 and U.S. PatentPublication Nos. 2009-0013547 (filed 9 Jul. 2007), 2009-0013548 (filed21 Dec. 2007) the entirety of which is hereby incorporated by referenceherein.

In one embodiment, the base 20 of the PCMM 10 may be situated on asupport surface, such as a table, floor, wall or any other stablesurface. In another embodiment, as shown in FIG. 2, the base 20A may bepositioned on a mobile unit 14, allowing the PCMM 10A to be convenientlymoved from one location to another. In such arrangements, the base 20Amay be secured to the mobile unit 14 in a fixed manner (e.g. bolted,fastened or otherwise attached at one or more locations). Further, themobile unit 14 may be configured with retractable or drop-down wheels 16that facilitate in moving the PCMM 10A. When properly positioned at thedesired location, the wheels 16 may be retracted and rigid support legs(not shown) that can used to secure the PCMM 10A in a fixed and stableposition in preparation for the acquisition of coordinate data.Additional details of this embodiment of the PCMM 10 can be found inU.S. Pat. No. 7,152,456 (issued 26 Dec. 2006) the entirety of which ishereby incorporated by reference herein.

With continued reference to FIGS. 1 and 2, in various embodiments of thePCMM 10, the various devices which may be used for coordinateacquisition, such as the probe 32, may be configured to be manuallydisconnected and reconnected from the PCMM 10 such that a user canchange probes without specialized tools. Thus, a user can quickly andeasily remove one probe and replace it with another probe. Such aconnection may comprise any quick disconnect or manual disconnectdevice. This rapid connection capability of a probe can be particularlyadvantageous in a PCMM that can be used for a wide variety of measuringtechniques (e.g. measurements requiring physical contact of the probewith a surface followed by measurements requiring only optical contactof the probe) in a relatively short period of time. Further detailsregarding probes and rapid connection capability can be found in U.S.patent application Ser. No. 12/057,918 (filed 28 Mar. 2008), theentirety of which being herein incorporated by reference.

In the embodiment of FIGS. 1 and 2, the probe 30 also comprises buttons66, which are configured to be accessible by a user. By pressing one ormore of the buttons 66 singly, multiply, or in a preset sequence, theuser can input various commands to the PCMM 10. In some embodiments, thebuttons 66 can be used to indicate that one or more coordinate readingsare ready to be recorded. In other embodiments, the buttons 66 can beused to indicate that the location being measured is a home position andthat other positions should be measured relative to the home position.In still other embodiments, the buttons 66 may be used to turn on or offthe PCMM 10. In other embodiments, the buttons 66 can be programmable tomeet a user's specific needs. The location of the buttons 66 on theprobe 30 can be advantageous in that a user need not access the base 20or a computer in order to activate various functions of the PCMM 10while using the probe 32 or more generally the coordinate acquisitionmember 30. This positioning may be particularly advantageous inembodiments of PCMM having transfer members 24, 26, or 28 that areparticularly long, thus placing the base 20 out of reach for a user ofthe coordinate acquisition member 30. In some embodiments of the PCMM10, any number of user input buttons (for example having more or fewerthan the three illustrated in FIG. 1), can be provided, which may beplaced in various other positions on the coordinate acquisition member30 or anywhere on the PCMM 10. Other embodiments of PCMM can includeother user input devices positioned on the PCMM 10 or the coordinateacquisition member 30, such as switches, rotary dials, or touch pads inplace of, or in addition to user input buttons.

FIGS. 3-5, illustrate several embodiments of probes 32 comprisingmodules or devices configured to provide information relating todetecting contact, as well as other capabilities. As used herein, theterm “modules” or “devices” refer to logic embodied by hardware orsoftware (including firmware), or to a combination of both hardware andsoftware, or to a collection of software instructions. Softwareinstructions may be embedded in firmware, such as an EPROM, and executedby a processor. It will be further appreciated that hardware modules mayinclude connected logic units, such as gates and flip-flops, and/or mayinclude programmable units, such as programmable gate arrays orprocessors. The modules described herein can be implemented as softwaremodules, or may be represented in hardware or firmware. Generally, themodules described herein refer to logical modules that may be combinedwith other modules or divided into sub-modules despite their physicalorganization or storage.

FIG. 3 schematically illustrates one embodiment of an improved probe 32.The probe 32 comprises a probe carriage 100, a probe mount 101, a probeneck 105, and a probe tip 108. The probe carriage 100 can be a last tubeof the PCMM 10, and can be configured to house various modules that, forexample, sense vibration, obtain real-time data, and/or provideinformation relating to calibrating the probe with the PCMM, etc. Theprobe mount 101 is configured to attach the probe 32 to the PCMM 10, orother embodiments of PCMMs or CMMs described herein or otherwise knownin the art. Similarly, the other probes described herein can also beapplied to various PCMMs or CMMs. The connection provided by the probemount 101 can be a permanent connection, a reversible connection, arapid connection, or a similar form of connection. The probe neck 105 isconfigured to connect the probe tip 108 with the probe carriage 100. Insome embodiments as will be discussed below, the probe neck 105 can beconfigured to include modules that, for example, obtain the temperatureof the probe 32. In other embodiments the probe neck 105 can besubstantially solid, possibly providing only a narrow bore for thepassage of one or more wires. The probe tip 108 can form an end of theprobe 32 and can be configured to engage surfaces of a selected objectand/or generate coordinate data on the basis of probe contact as isknown in the art. The probe tip 108 can typically form a circular ballor sphere, but other shapes are possible.

Still with reference to FIG. 3, the probe carriage 100 further comprisesa vibration detection device 200. Although the vibration detectiondevice 200 is described herein as an accelerometer, other methods ofvibration detection known in the art can be used such as variousconfigurations of capacitive touch sensors or MEMS microphones. In oneembodiment, the accelerometer 200 can detect vibration using a structuresuspended with springs having differential capacitors that provide asignal indicative of the position of the structure, and accordingly thedeflection of the springs. In an additional embodiment the accelerometer200 comprises a micro electro-mechanical system (MEMS) that comprises acantilever beam with a proof mass (or seismic mass) positioned within agas sealed environment that provides for damping. Under the influence ofexternal acceleration the proof mass deflects from its neutral position.This deflection can be measured in an analog or digital manner. In onearrangement, the capacitance between a set of fixed beams and a set ofbeams attached to the proof mass is measured. In another arrangement,piezoresistors can be integrated into the springs to detect springdeformation. As is know in the art, most accelerometers operatein-plane, that is, they are designed to be sensitive only to a directionin the plane of the device. By integrating two devices perpendicularlyon a single plate a two-axis accelerometer can be made. By adding anadditional out-of-plane device three axes can be measured. Those of theskill in the art will recognize other embodiments of the accelerometer200 that can be used in light of the disclosure herein.

As shown in FIG. 3, the accelerometer 200 can connect to the probe mount101 through a bus line 109, allowing information from the accelerometerto be transmitted from the probe 32 to the PCMM 10 as well as any otherdesirable units or sub-components. Accordingly, the accelerometer 200can be operatively connected to other elements of the PCMM 10 such asthe devices for measuring rotational position described above. In someembodiments the operative connection can be direct, with a signalpassing from the accelerometer 200 to the sub-components unaltered. Inother embodiments the operative connection can be indirect, perhapspassing through a processor (described below) that may alter the signalor generate a new signal to pass to the sub-components at leastpartially dependent on a signal from the accelerometer 200. In furtherembodiments, the operative connection can be indirect, passing through aseries of intermediate components.

In this embodiment, being proximal to the probe tip 108, theaccelerometer 200 can advantageously detect vibrations on or from theprobe tip 108. For instance, in some embodiments the accelerometer canbe rigidly attached to the probe tip 108, either directly or indirectly.Such rigid attachment can minimize damping of vibrations propagatingfrom the probe tip 108 to the accelerometer 200. Further, theaccelerometer 200 can be connected in such a manner that minimizescontinuing vibrations after an initial acceleration of the probe tip108. For example, in some embodiments the accelerometer 200 can bedirectly supported, and not cantilevered or suspended.

The accelerometer 200 can be configured to measure vibrations in avariety of directions, including three translational and threerotational directions. However, in some embodiments fewer vibrationaldirections can be detected. For example, as rotational vibrations may beless significant in operation, in some embodiments only the threetranslational vibrations can be measured. Further, in some embodiments asimplified accelerometer 200 may be desired, in which case onlytranslational vibrations parallel to the probe neck 105 can be measured.More generally, the vibrations measured can vary depending on theintended use of the PCMM 10.

Upon detection of a vibration, the accelerometer 200 can indicate thisactivity to the PCMM 10, and thus trigger a measurement of the positionof the probe tip 108. As described above, in response to a trigger, therotational degree of the articulation members 40, 42, 44, 46, 48, 50 canbe recorded and/or taken. In some embodiments the accelerometer canprovide this indication directly to e.g. encoders associated with thearticulation members. In other embodiments, the indication can beprovided indirectly, e.g. via a processor on the probe 32 (discussedfurther below) or some other device on the PCMM 10. In furtherembodiments, the encoders can be continuously outputting a rotationalposition to a separate processor, which is also operatively connected tothe accelerometer 200. In this case, the accelerometer can trigger therecording of desired data such as rotational position.

As the probe 32 will experience vibrations and accelerations evenwithout contacting an object to be measured, the accelerometer 200 (andpossibly associated devices) can indicate contact only under particularcircumstances. For example, in some embodiments the probe 32 can beconfigured to indicate contact when the accelerometer 200 measures anacceleration of at least a particular threshold amplitude. In otherembodiments, the probe 32 can indicate contact when the accelerationchanges by a particular amount in a particular amount of time (e.g. athreshold jerk). Further, in some embodiments a threshold duration ofthe acceleration or jerk can be required for the probe 32 to indicatecontact. For example, in some embodiments only accelerations or jerkswith a sufficiently long duration indicate contact (minimum duration).Similarly, in some embodiments the acceleration or jerk must end (ordecline) after a certain duration of time (maximum duration). Evenfurther, in some embodiments a second contact can only be indicatedafter a certain cooldown time has passed since the last indicatedcontact (cooldown duration). The particular requirements for indicationof contact can be varied depending on the intended use of the PCMM 10.For example, if the PCMM 10 is automated then the probe 32 can beconfigured to take into account the actual or possible movement of thePCMM 10, and accordingly ignore accelerations and vibrations causedsolely by this movement. If the PCMM 10 is manually operated, it can besimilarly configured in light of the different expected movements. Forexample, the probe 32 can be configured to ignore vibrations caused bythe pressing of a button 66. Notably, the pressing of one of saidbuttons 66 can also signal the probe 32 to begin monitoring forvibrations from contact. In further embodiments, the probe 32 can beconfigured to ignore vibrations caused during periods of substantiallycontinued high vibrations that can reduce accuracy (as the PCMM can becalibrated under quasi-static conditions). More generally, in someembodiments the criteria for indicating contact can be configured tocheck for a new vibration, distinct from other ongoing vibrations.

In one particular example, two acceleration measurements taken closetogether in time can be compared. If the magnitude of the difference inthe two acceleration measurements is above a specified threshold, thenthe probe 32 can indicate contact. In even more specific examples, thedifference in accelerations can be a difference in measured accelerationvectors, and the magnitude of the difference can be the norm of thedifference. However, in other embodiments the differences inacceleration can be analyzed differently, such as by summing theabsolute values of the change in acceleration in each componentdirection. The threshold level and the time interval betweenmeasurements can vary with the PCMM 10, the probe 32, and their intendeduse. In some embodiments the comparison can be implemented in hardwarewhere, for example, one acceleration measurement is delayed and the twoaccelerations are compared by a comparator circuit.

Advantageously, a probe 32 that is triggered by such vibrations can, insome embodiments, have no moving parts. In other embodiments, the probe32 can have fewer moving parts. For example, in the embodimentsdescribed herein the probe 32 can optionally lack a vibrator or someother device that purposefully initiates vibrations in the probe 32 orPCMM 10 (independent of contact vibrations). The reduction in movingparts can make the probe 32 less expensive to produce and more reliableover the lifetime of the probe 32. Further, in the embodiments of theprobe 32 described herein, the probe 32 can optionally operate as astandard hard contact probe when operated in a different mode, possiblycontrolled by modules or devices on the probe 32 or elsewhere on the CMM10, as further described below.

FIG. 3A depicts another embodiment of a probe 32, similar to thatdepicted in FIG. 3 and with the optional variations described relativethereto, except where otherwise stated. As depicted, the carriage 100can also include several modules configured, for example, to providedata uniquely identifying the probe 32, facilitate calibration of theprobe with the PCMM 10, etc. The probe carriage 100 comprises aprocessor 102, a solid-state memory device 104, a temperature sensor106, and an accelerometer 200. The solid-state memory device 104, thetemperature sensor 106, and the accelerometer 200 are connected to theprocessor 102 using bus lines 103, 111, 110 respectively.

In some embodiments, the processor 102, memory 104, temperature sensor106, and accelerometer 200 may all be integrated in one chip. In otherembodiments, they may be separate components mounted on a circuit boardor electronically coupled, such as with a wired connection. In otherembodiments, only one, two, or three of the components may be presentand others not required.

The bus line 109 can connect the processor 102 to the probe mount 101such that any information obtained by the processor 102 from thesolid-state memory device 104, the temperature sensor 106, and theaccelerometer 200 is transmitted from the probe 32 to the PCMM 10 towhich the probe 32 is attached. In one embodiment, the PCMM 10 can usethe transmitted information to calibrate the probe 32 with the PCMM 10.In another embodiment, the PCMM 10 can retransmit the obtainedinformation to a general purpose computer (not shown) configured tocalibrate the probe 32 with the PCMM 10. In another embodiment, the PCMM10 can use the information the PCMM obtains from the processor 102 toretrieve calibration or nominal data related to the probe 32 that isstored in a different media such as a memory key, hard disk, or acomputer, as will be further described below. In further embodiments, asdiscussed above, the PCMM 10 uses the information to indicate contactwith an object to be measured and accordingly measures the position ofthe probe tip 108 at that time.

As illustrated in FIG. 3A, the processor 102 in one embodiment is ageneral purpose central processing unit (CPU) configured to controloperations of various modules of the probe 32, including the solid-statememory device 104, the temperature sensor 106, and accelerometer 200.Other examples of processors could include, but are not limited to,separate or individual processing cores, separate or distributedprocessing logic, general purpose processors, special purposeprocessors, application specific integrated circuits (ASICs) withprocessing functionality, memory controllers, system controllers, etc.As shown in FIG. 3A, the processor 102 can be connected to thesolid-state memory device 104 through bus line 103, the temperaturesensor 106 through the bus line 111, and the accelerometer 200 throughbus line 110. In one embodiment, the processor 102 is configured tocontrol the operation of the solid-state memory device 104, thetemperature sensor 106, and the accelerometer 200 using connections 103,111 and 110. In another embodiment, the processor 102 controls thesolid-state memory device 104, for example, by sending instruction toread a particular address in the solid-state memory device 104 andreceiving a data signal from the solid-state memory device 104corresponding to the address sent by the processor 102. In someembodiments, the processor 102 transmits the data it receives from thesolid-state memory device 104 to the PCMM 10 using the bus line 109. Inanother embodiment, the processor 102 obtains a temperature reading fromthe temperature sensor 106 using the bus line 103 and transmits thetemperature reading to the PCMM 10 using the bus line 109. In otherembodiments, data transfer to and from the processor 102 can be madewirelessly using a wireless data transmission protocol.

The solid-state memory device 104 can be capable of accepting data,storing the data, and subsequently providing the data. The solid-statememory device 104 as illustrated in FIG. 3A depicts a non-volatileelectrically erasable programmable read-only memory (EEPROM) device. Theprocessor 102 or another memory controller can selectively write orerase any part of the EEPROM without the need to write or erase theentire EEPROM. Although EEPROM is preferably used in connection with theprobe 32 in the various embodiments contained herein, the probe 32 canbe configured to comprise any suitable non-volatile electronic datastorage device, including, but not limited to, tape, hard disk, opticaldisk, Flash memory, programmable read-only memory (PROM), erasable PROM(EPROM), etc. In one embodiment, the sold-state memory device 104 is anEEPROM device comprising a 48-bit laser etched serial number. Aspreviously mentioned, the processor 102 can be configured to control theoperation of the solid-state memory device 104 by sending controlsignals through the control lines 103, such as, for example,instructions for the solid-state memory device 104 to write datatransmitted through a data bus (not shown) to a memory cell address sentthrough the address bus (not shown). In certain embodiments, theprocessor 102 controls the operation of the solid-state memory device104 using separate system and memory controllers (not shown).

Still with reference to FIG. 3A, the solid-state memory device 104 inone embodiment can be configured to include a unique serial or productnumber, machine readable data that uniquely identifies the particularprobe 32 on which the solid-state memory device 104 is located. Theunique serial number allows individual serialization of all of theimproved probes to advantageously allow subsequent identification ofeach one of the probes 32. In certain embodiments, the unique serialnumber can even identify individual probes 32 that belong to the sametype or category. For example, in some embodiments the solid-statememory device 104 can include information identifying it as including avibration detection device 200.

A solid-state memory device 104 comprising a machine readable uniqueserial number identifying the probe 32 has several advantages. Aspreviously mentioned, if the probe 32 is mounted to the PCMM 10 for thefirst time, or if a new probe 32 is used for the first time, the probe32 must be calibrated with the PCMM 10. Each probe 32 has nominal datarelating to characteristics of the probe 32, such as, for example,length, category, type, offsets, width, thickness, etc. that is usuallycontained in different media such as disks, memory keys, etc. Thisnominal data is used as a starting point to calibrate the probe 32 withthe PCMM 10. In some embodiments, the nominal data is stored in acomputer that is connected to the PCMM 10. In other embodiments, thenominal data is stored in a storage area located on the PCMM 10. In yetother embodiments, the nominal data for the probe 32 is stored in adifferent storage media along with the machine readable unique serialnumber for that particular probe 32. During the calibration process, thePCMM 10 can obtain the nominal data for the probe 32 by first readingthe machine readable unique serial number from the probe 32 andobtaining the nominal data located on different media which contains thesame unique serial number. As such, the machine readable unique serialnumber identifying the probe 32 can be used to better match the probe 32with the corresponding nominal data stored on a different media thanconventional systems, some of which do not distinguish probes 32 of thesame type or category.

Further in other embodiments, the machine readable serial numberuniquely identifying the probe 32 can be used to match calibration datawith the probe 32. When the PCMM 10 calibrates the probe 32, the resultcan be data that provides translation from the end of the PCMM 10 to thetip of the probe 32. In further embodiments, the calibration data canindicate vibration characteristics between the PCMM 10 and the probe 32,such as the propensity for vibrations to propagate between the two,vibrations created by the contactless movement of the PCMM 10, and othercharacteristics. The calibration data can therefore be unique to theparticular PCMM 10 and probe 32 combination. As with nominal data, thecalibration data is also typically stored in media different from thecoordinate acquisition device 30, such as, for example, a memory key,hard disk on a computer, or storage area located on the PCMM 10, etc. Insome embodiments, the PCMM 10 stores the calibration data for a probe 32on the different media along with the machine readable serial number ofthe particular probe 32. When the probe 32 is remounted to the PCMM 10,the PCMM 10, as with the nominal data described above, can obtain thecalibration data that is specific to the probe 32 from the differentmedia by first reading the machine readable unique serial number fromthe probe 32 and obtaining the calibration data that contains the sameserial number.

Although the machine readable serial number is stored in the solid-statememory device 104 in the previously disclosed embodiments, the machinereadable serial number in other embodiments can be located elsewhere onthe probe 32. In some embodiments, the serial number is located onanother module located in the probe carriage 100, such as, for example,the processor 102. In other embodiments, the machine readable serialnumber can be provided by an integrated package of software and/orhardware similar to systems used in warehouse operations, such as, forexample, bar codes and RFID tags.

In still other embodiments with respect to FIG. 3A, the solid-statememory device 104 can be configured to store nominal data. In oneembodiment, the processor 102 stores the nominal data relating tophysical characteristics of the probe 32 into the solid-state memorydevice 104, for example, using the control line 103. The nominal datacan be written in the solid-state device 104 during the manufacturestage of the probe 32. In other embodiments, nominal data is writteninto the solid-state memory device 104 after the probe 32 is assembled,for example, using a general purpose computer configured to writenominal data into the solid-state memory device 104. In someembodiments, an RFID tag on the probe 32 can store the machine readableserial number and/or nominal data. The PCMM 10 can wirelessly retrievethe serial number and/or nominal data from the RFID tag. In otherembodiments, communication between the CMM and probe can occur throughother wireless protocols, such as WiFi, Bluetooth, or RF. In still otherembodiments, the PCMM 10 first reads the machine readable unique serialnumber from the solid-state device 104, then obtains the nominal databased on the machine readable unique serial number, for example from adifferent media such as a memory key or another computer, and stores thenominal data into the solid-state device 104 such that the probe 32 willretain nominal data for use in subsequent calibrations. A solid-statememory device 104 configured to store nominal data eliminates the needto maintain a separate media to store nominal data, thereby reducing thedifficulty of managing large number of probes and their associatednominal data.

Still with reference to FIG. 3A, the probe 32 can use the temperaturesensor 106 to measure the temperature of the probe 32 and provide thetemperature information to the PCMM 10. As illustrated in FIG. 1, theposition of the probe 32 in space at a given instant can be calculatedif the length of each transfer member 24, 26, and 28 and the length ofthe probe 32 are known. The length and other physical parameters of theprobe 32 can be obtained by the PCMM 10 during calibration, for example,by reading nominal data from the solid-state memory device 104. However,the length of the probe 32 may change, for example, by expanding inresponse to an increase in temperature. In some embodiments, thetransfer members 24, 26, and 28 of the PCMM 10 and the probe 32 arecomposed of different material with different heating coefficients and,therefore, expand and/or contract in response to temperature at adifferent rates. In other embodiments, the transfer members 24, 26, and28 and the probe 32 are composed of the same material but expand and/orcontract at a different rate because the temperature of the probe 32 canbe different from temperature of the PCMM 10, for example, due to theheat generated within the PCMM 10.

The PCMM 10 can use the temperature sensor 106 to compensate for theexpansion or contraction of the probe 32 due to changes in temperature.In one embodiment, the solid-state memory device 104 contains nominaldata related to the temperature characteristics of the probe 32, suchas, for example, heating coefficient information, length at a certaindefault temperature, etc. At any given time, the PCMM 10 can obtain thetemperature of the probe 32 from the temperature sensor 106, obtain thecoefficient of thermal expansion of the probe 32 from the solid-statememory device 104, and calculate any changes in the physicalcharacteristics of the probe 32 using the obtained temperature and thecoefficient of thermal expansion of the probe 32. In some embodiments,the temperature of the probe 32 and the coefficient of thermal expansionof the probe 32 are transmitted, for example by the processor 102, to ageneral purpose computer attached to the PCMM 10 in order to calculatethe changes in physical characteristics of the probe 32. In otherembodiments, the PCMM 10 or the general purpose computer obtain thecoefficient of thermal expansion of the probe 32 from a different media,such as, for example, a memory key, a disk, a database, etc. In otherembodiments, the PCMM 10 and/or general purpose computer use the uniquemachine readable serial number of the probe 32 to obtain the appropriatecoefficient of thermal expansion of the probe 32 from the differentmedia. Compensating for the expansions or contractions of the probe 32due to changes in temperature using the temperature sensor 106 in theabove-described manner eliminates the need for the PCMM 10 torecalibrate the probe 32 in response to temperature effects. Further,other changes to the probe 32 can be computed from changes intemperature, such as the behavior of sensors such as the vibrationdetection device 200.

Further, as discussed above in regard to detection of contact with anobject to be measured, the processor 102 can be configured to determinewhether a given signal from the vibration detection device 200 should beconsidered to indicate contact. The various possible rules describedabove can be inputted into the processor 102 as software or hardware. Insome embodiments the processor 102 can further calibrate the rules forcontact detection by continuously examining the output of the vibrationdetection device 200 during movement of the PCMM 10 absent contact, forexample during a vibration calibration procedure. The vibrationcalibration procedure can involve movement of the PCMM 10 in a mannersimilar to that during normal operation, absent actual contact with anyobject. This can be used to appropriately set the various thresholds andother possible contact detection parameters such as those describedherein.

Although the probe 32 of FIG. 2 comprises the processor 102, solid-statememory device 104, temperature sensor 106 and accelerometer 200 asseparate modules located on the probe carriage 100, other configurationsare possible. For example, some or all of the modules the processor 102,solid-state memory device 104, temperature sensor 106 and accelerometer200 may be located on a different area of the probe 32 or the PCMM 10(as further described below). Further still, the probe 32 may comprisemodules that combine the functions of one or more of the processor 102,solid-state memory device 104, temperature sensor 106 and accelerometer200.

Other configurations not explicitly mentioned above or herein are alsopossible. For example, in some embodiments additional coordinate sensorscan be included on the coordinate acquisition member 30, and can also beassociated with the above described devices and modules. Similarly,additional sensors can be included to monitor the state of variousportions of the PCMM 10. Further devices and modules, and thearrangement and use thereof, is described in U.S. patent applicationSer. No. 12/057,918, filed Mar. 28, 2008, which is incorporated hereinby reference in its entirety as stated above.

FIG. 4 depicts another embodiment of an improved probe 32. As depicted,the vibration detection device 200 can be located within the probe tip108. As the vibration detection device 200 is further distanced from theprobe mount 101, they can connect via two bus lines in series 109A,109B. The embodiment depicted in FIG. 4 can have similar features to theembodiments depicted in FIGS. 3 and 3A, and can operate in a similarmanner and with the optional variations described relative thereto,except where otherwise stated. In particular reference to the details ofthe embodiment in FIG. 3A, in a preferred embodiment the vibrationdetection device 200 can be separated from the other modules and deviceswhere, as depicted, it is located within the probe tip 108. However, inother embodiments each of the devices and modules can be held within theprobe tip.

FIG. 5 depicts another embodiment of a probe 32, again similar to theembodiments depicted in FIGS. 3 and 3A and with the optional variationsdescribed relative thereto, except where otherwise stated. As depicted,the vibration detection device 200 can be located within the probe mount101. Accordingly, the vibration detection device 200 can be generallyseparate from the probe 32, as in some embodiments the probe 32 candetach from the probe mount 101 and the PCMM 10. Accordingly, the PCMM10 can detect vibrations even when using standard prior art probes thatlack a vibration detection device (e.g., a hard probe). Similarly, wherethe vibration detection device 200 is on the probe 32, the probe 32 canbe used with prior art PCMM arms to detect vibration.

Generally, moving the vibration detection device 200 further from thetip 108 can advantageously reduce error and delay in the transmission ofthe signal therefrom, as the signal does not travel as far. However, thegreater distance between the vibration detection device 200 and theprobe tip 108 can increase the error between the measured vibrations andthe actual vibrations at the tip.

Although the above-disclosed embodiments of the present teachings haveshown, described, and pointed out the fundamental novel features of theinvention as applied to the above-disclosed embodiments, it should beunderstood that various omissions, substitutions, and changes in theform of the detail of the devices, systems, and/or methods illustratedmay be made by those skilled in the art without departing from the scopeof the present invention. Consequently, the scope of the inventionshould not be limited to the foregoing description, but should bedefined by the appended claims.

All publications and patent applications mentioned in this specificationare indicative of the level of skill of those skilled in the art towhich this invention pertains. All publications and patent applicationsare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

The various devices, methods, procedures, and techniques described aboveprovide a number of ways to carry out the invention. Of course, it is tobe understood that not necessarily all objectives or advantagesdescribed may be achieved in accordance with any particular embodimentdescribed herein. Also, although the invention has been disclosed in thecontext of certain embodiments and examples, it will be understood bythose skilled in the art that the invention extends beyond thespecifically disclosed embodiments to other alternative embodiments,combinations, sub-combinations and/or uses and obvious modifications andequivalents thereof. Accordingly, the invention is not intended to belimited by the specific disclosures of preferred embodiments herein.

1. A articulated arm system comprising: an articulated measuring armcomprising a plurality of interconnected support arm segments moveableabout a plurality of axes; a plurality of rotational angle sensorsmounted on the articulated measuring arm configured to measurerotational position between the support arm segments; and a vibrationdetection device attached to the articulated measuring arm near an endof the articulated measuring arm, the vibration detection device beingoperatively connected to the sensors such that the sensors will output arotational position upon detection of a new vibration exceeding athreshold amplitude.
 2. The system of claim 1, further comprising acoordinate acquisition member at an end of the articulated measuringarm.
 3. The system of claim 2, wherein the vibration detection device isdisposed on the coordinate acquisition member.
 4. The system of claim 2,wherein the coordinate acquisition member comprises a hard probe.
 5. Thesystem of claim 4, wherein the coordinate acquisition member furthercomprises a device for detecting position and/or contact distinct fromthe vibration detection device.
 6. The system of claim 1, wherein atleast one of the sensors is an optical encoder.
 7. The system of claim1, wherein the vibration detection device is disposed on the articulatedmeasuring arm.
 8. The system of claim 2, wherein the coordinateacquisition member is removable.
 9. The system of claim 2, wherein thevibration detection device is disposed within the coordinate acquisitionmember.
 10. The system of claim 4, wherein the vibration detectiondevice is disposed within the hard probe.
 11. The system of claim 2,wherein the vibration detection device is rigidly attached to thecoordinate acquisition member.
 12. The system of claim 1, wherein thevibration detection device is an accelerometer.
 13. The system of claim3, wherein the coordinate acquisition member comprises a probe tip andthe vibration detection devices is disposed within the probe tip.
 14. Amethod of operating an articulated arm system comprising: contacting anitem to be measured with an articulated measuring arm comprising aplurality of interconnected support arm segments moveable about aplurality of axes; sensing a new vibration at an end of the measuringarm upon contact with the item; generating a triggering signal inresponse to the new vibration; and automatically measuring a position ofthe end of the measuring arm in response to the triggering signal. 15.The method of claim 14, wherein the triggering signal indicates contactwith the item.
 16. The method of claim 14, further comprising the stepof storing the measured position.
 17. The method of claim 14, whereinthe step of measuring further comprises storing the measured position.18. The method of claim 14, wherein the step of automatically measuringis performed with an electronic encoder.
 19. The method of claim 14,further comprising the step of determining whether a sensed newvibration indicates contact with the item.
 20. The method of claim 19,wherein the step of determining further comprises checking for athreshold amplitude.
 21. The method of claim 19, wherein the step ofdetermining further comprises checking for a minimum duration of anacceleration.
 22. The method of claim 19, wherein the step ofdetermining further comprises checking for a maximum duration of anacceleration.
 23. The method of claim 19, wherein the step ofdetermining further comprises ignoring vibrations during periods ofsubstantially continued high vibrations.
 24. The method of claim 19,wherein the step of determining further comprises checking for passageof a cooldown duration.
 25. A probe configured for use with a coordinatemeasurement machine comprising: a probe tip comprising an accelerometer;a probe neck connecting the probe tip to a probe body; and a mountingportion configured to mount the probe body to a coordinate measuringmachine, the mounting portion comprising a connect device and a dataport.
 26. The probe of claim 25, wherein the accelerometer and data portare configured to output a trigger signal upon detection of a newvibration exceeding a threshold amplitude.
 27. The probe of claim 25,further comprising a device for detecting position and/or contactdistinct from the accelerometer.
 28. The probe of claim 25, wherein theprobe tip is a hard probe tip.